1. Technical Field
This invention generally relates to distributed applications, for example, computer remote conference system or remote desktop presentation system, which are distributively processed by a plurality of computers, and, particularly, to a method and mechanism for indicating an item displayed on a screen by a user.
2. Description of the Related Art
With the development of communications technology, it has become possible to obtain a fast, highly reliable communication network having less difference in time between a sender and a receiver at a reasonable price. With the background of the improvement of such basic communication technologies, it has become possible to handle shared data by mutually connecting computers assigned to geographically distributed places and by sharing information, such as text, graphics, and images, with computers. Such a technique is called distributed application.
An important feature of the distributed application is the display in real time of identical information on screens or in windows of a plurality of computers, which are mutually connected. Displaying identical screens or windows on screens of computers, which are mutually connected in a distributed system, is called "screen sharing" or "window sharing."
Furthermore, frequently moving objects exist on shared screen displays. These objects are, for example, cursors or pointers, or actual graphical data. They are used to transfer the users' intentions by moving them. Hereafter, they are referred to as pointing objects.
Under a distributed application mechanism, users have conversations with shared "screens" or "windows" as shared data. At this time, users carry out effective conversations on shared data by using an auxiliary audio means, such as a telephone. The users experience less delay due to the use of an auxiliary audio transmission media, such as a telephone. On the other hand, the users cannot ignore overhead for the mutual exchange of information with respect to information displayed on-screen. The actual difference in display time between a sender and a receiver is not negligible. In a channel connecting to a remote site, information can be delayed due to various reasons. Since the speed of light is not infinite, there are situations where these delays cannot be avoided. For example, in international telephone calls using satellite lines, a certain amount of delay occurs, the existence of which people can feel. This difference in time is not significant in the case where a local area network, which does not generate much difference in time in transmission, is used. But, in general, some delays in a channel can be noticed by the user. A dislocation of the position of indicators in two different locations at an identical time can be such a great matter that it cannot be said the identical information is shared.
In a conventional system, users manipulate the system on the assumption that such a difference in time occurs. But in this case, users have to predict how the display of the remote user is seen at all times. It was not a comfortable environment. This kind of problem becomes particularly remarkable when a pointing object is used.
Furthermore, Japanese Patent Application No. 3-222394 relates to this invention. The invention of this application discloses the sharing of applications in a distributed computing environment. Here, the screen is also shared with a plurality of computer systems. However, this application does not mention anything about the pointing object. In addition, PUPA No. 4-284791 discloses the display of a pointing object on the receiving side in response to a pointing object on a transmission side by screen sharing. However, nothing is disclosed with respect to a device for sharing a pointing object by taking communication time difference into account.